1. Field of the Invention
The present invention relates to methods of treating individuals suffering from a variety of conditions wherein inhibiting reuptake of norepinephrine provides a benefit. In particular, the present invention relates to methods of treatment comprising administration of a compound, such as (S,S) reboxetine, to an individual, wherein the compound has a high pharmacological selectivity with respect to norepinephrine reuptake sites compared to serotonin reuptake sites. The present invention also relates to a composition containing the compound and to a preparation of a medicaments containing the composition.
2. Brief Description of Related Technology
Many types of depression, mental, behavioral, and neurological disorders originate from disturbances in brain circuits that convey-signals using certain monoamine neurotransmitters. Monoamine neurotransmitters include, for example, norepinephrine (noradrenaline), serotonin (5-HT), and dopamine. Lower-than-normal levels of norepinephrine are associated with a variety of symptoms including lack of energy, motivation, and interest in life. Thus, a normal level of norepinephrine is essential to maintaining drive and capacity for reward.
These neurotransmitters travel from the terminal of a neuron across a small gap (i.e., the synaptic cleft) and bind to receptor molecules on the surface of a second neuron. This binding elicits intracellular changes that initiate or activate a response or change in the postsynaptic neuron. Inactivation occurs primarily by transport (i.e., reuptake) of the neurotransmitter back into the presynaptic neuron. Abnormality in noradrenergic transmission results in various types of depression, mental, behavioral, and neurological disorders attributed to a variety of symptoms including a lack of energy, motivation, and interest in life. See generally, R. J. Baldessarini, “Drugs and the Treatment of Psychiatric Disorders: Depression and Mania” in Goodman and Gilman's The Pharmacological Basis of Therapeutics, McGraw-Hill. N.Y., N.Y., pp. 432–439 (1996).
Reboxetine (i.e. 2-[(2-ethoxyphenoxy)(phenyl)methyl]morpholine) raises the concentration of physiologically active norepinephrine by preventing reuptake of norepinephrine, for example. Reboxetine is a norepinephrine reuptake inhibitor and has been shown to be effective in the short-term (i.e., less than eight weeks) and long-term treatment of depression. In fact, reboxetine has been shown to have effectiveness that is similar to fluoxetine, imipramine, and desipramine, commonly prescribed antidepressants, in both adults and elderly patients. See S. A. Montgomery, Reboxetine: Additional Benefits to the Depressed Patient, Psychopharmocol (Oxf) 11:4 Suppl., S9–15 (Abstract) (1997).
Antidepressant drugs are sometimes divided into “generations.” The first generation included the monoamine oxidase inhibitors (such as isocarboxazid and phenylhydrazine) and tricyclic agents (such as imipramine). The second generation of antidepressant drugs included compounds such as mianserin and trazodone. The third generation has included drugs called selective reuptake inhibitors (e.g. fluoxetine, sertraline, paroxetine, and reboxetine). Those drugs were characterized by relatively selective action on only one of the three main monoamine systems thought to be involved in depression (i.e. 5-HT (serotonin), noradrenaline (norepinephrine), and dopamine). APP Textbook of Psychopharmacology (A. F. Schatzberg and C. B. Nemeroff), American Psychiatric Press, 2d. ed., (1998); Lexicon of Psychiatry, Nuerology and the Neurosciences (F. J. Ayd, Jr.) Williams and Wilkins (1995). The antidepressant efficacy of reboxetine is evidenced by its ability to prevent resperine-induced blepharospasm and hypothermia in mice, down regulation of β-adrenergic receptors and desensitization of noradrenaline-coupled adenylate cyclase. See M. Brunello and G. Racagni, “Rationale for the Development of Noradrenaline Reuptake Inhibitors,” Human Psychophramacology, vol. 13, S-13–519, Supp. 13–519 (1998).
According to a survey by Brian E. Leonard, desipramine, maprotiline, and lofepramine are relatively selective norepinephrine reuptake inhibitors with proven efficacy. These materials increase brain noradrenaline and thereby function to relieve depression. Mianserin and mirtazepine also show antidepressant-like effects by increasing noradrenaline availability by means of blocking the pre-synaptic α2-adrenoceptors. Still further, oxaprotiline, fezolamine, and tomoxetine are potent and selective norepinephrine reuptake inhibitors that lack neurotransmitter receptor interactions and, thus, do not cause many of the side effects characteristic of classical tricyclic antidepressants. See Brian E. Leonard, “The Role of Noradrenaline in Depression: A Review,” Journal of Psychopharmocology, vol. 11, no. 4 (Suppl.), pp. S39–S47 (1997)
Reboxetine also is a selective norepinephrine reuptake inhibitor, which also produces fewer of the side effects associated with the administration of classical tricyclic antidepressants. The antidepressant efficacy of reboxetine is evidenced by its ability to prevent resperine-induced blepharospasm and hypothermia in mice, down regulation of β-adrenergic receptors and desensitization of noradrenaline-coupled adenylate cyclase. See M. Brunello and G. Racagni, “Rationale for the Development of Noradrenaline Reuptake Inhibitors,” Human Psychophramacology, vol. 13 (Supp.) 13–519 (1998).
Reboxetine generally is described in Melloni et al. U.S. Pat. Nos. 4,229,449, 5,068,433, and 5,391,735, and in GB 2,167,407, the disclosures of which are hereby incorporated by reference. Chemically, reboxetine has two chiral centers and, therefore, exists as two enantiomeric pairs of diastereomers, shown below as isomers (I) through (IV):
